/*
 * Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
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 *
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 */

package java.io;

import java.util.Arrays;

/**
 * This class implements a character buffer that can be used as an Writer.
 * The buffer automatically grows when data is written to the stream.  The data
 * can be retrieved using toCharArray() and toString().
 * <P>
 * Note: Invoking close() on this class has no effect, and methods
 * of this class can be called after the stream has closed
 * without generating an IOException.
 *
 * @author Herb Jellinek
 * @since JDK1.1
 */
public class CharArrayWriter extends Writer {

  /**
   * The buffer where data is stored.
   */
  protected char buf[];

  /**
   * The number of chars in the buffer.
   */
  protected int count;

  /**
   * Creates a new CharArrayWriter.
   */
  public CharArrayWriter() {
    this(32);
  }

  /**
   * Creates a new CharArrayWriter with the specified initial size.
   *
   * @param initialSize an int specifying the initial buffer size.
   * @throws IllegalArgumentException if initialSize is negative
   */
  public CharArrayWriter(int initialSize) {
    if (initialSize < 0) {
      throw new IllegalArgumentException("Negative initial size: "
          + initialSize);
    }
    buf = new char[initialSize];
  }

  /**
   * Writes a character to the buffer.
   */
  public void write(int c) {
    synchronized (lock) {
      int newcount = count + 1;
      if (newcount > buf.length) {
        buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
      }
      buf[count] = (char) c;
      count = newcount;
    }
  }

  /**
   * Writes characters to the buffer.
   *
   * @param c the data to be written
   * @param off the start offset in the data
   * @param len the number of chars that are written
   */
  public void write(char c[], int off, int len) {
    if ((off < 0) || (off > c.length) || (len < 0) ||
        ((off + len) > c.length) || ((off + len) < 0)) {
      throw new IndexOutOfBoundsException();
    } else if (len == 0) {
      return;
    }
    synchronized (lock) {
      int newcount = count + len;
      if (newcount > buf.length) {
        buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
      }
      System.arraycopy(c, off, buf, count, len);
      count = newcount;
    }
  }

  /**
   * Write a portion of a string to the buffer.
   *
   * @param str String to be written from
   * @param off Offset from which to start reading characters
   * @param len Number of characters to be written
   */
  public void write(String str, int off, int len) {
    synchronized (lock) {
      int newcount = count + len;
      if (newcount > buf.length) {
        buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
      }
      str.getChars(off, off + len, buf, count);
      count = newcount;
    }
  }

  /**
   * Writes the contents of the buffer to another character stream.
   *
   * @param out the output stream to write to
   * @throws IOException If an I/O error occurs.
   */
  public void writeTo(Writer out) throws IOException {
    synchronized (lock) {
      out.write(buf, 0, count);
    }
  }

  /**
   * Appends the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.toString()) </pre>
   *
   * <p> Depending on the specification of <tt>toString</tt> for the
   * character sequence <tt>csq</tt>, the entire sequence may not be
   * appended. For instance, invoking the <tt>toString</tt> method of a
   * character buffer will return a subsequence whose content depends upon
   * the buffer's position and limit.
   *
   * @param csq The character sequence to append.  If <tt>csq</tt> is <tt>null</tt>, then the four
   * characters <tt>"null"</tt> are appended to this writer.
   * @return This writer
   * @since 1.5
   */
  public CharArrayWriter append(CharSequence csq) {
    String s = (csq == null ? "null" : csq.toString());
    write(s, 0, s.length());
    return this;
  }

  /**
   * Appends a subsequence of the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq, start,
   * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
   * exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.subSequence(start, end).toString()) </pre>
   *
   * @param csq The character sequence from which a subsequence will be appended.  If <tt>csq</tt>
   * is <tt>null</tt>, then characters will be appended as if <tt>csq</tt> contained the four
   * characters <tt>"null"</tt>.
   * @param start The index of the first character in the subsequence
   * @param end The index of the character following the last character in the subsequence
   * @return This writer
   * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are negative,
   * <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt> is greater than
   * <tt>csq.length()</tt>
   * @since 1.5
   */
  public CharArrayWriter append(CharSequence csq, int start, int end) {
    String s = (csq == null ? "null" : csq).subSequence(start, end).toString();
    write(s, 0, s.length());
    return this;
  }

  /**
   * Appends the specified character to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(c)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(c) </pre>
   *
   * @param c The 16-bit character to append
   * @return This writer
   * @since 1.5
   */
  public CharArrayWriter append(char c) {
    write(c);
    return this;
  }

  /**
   * Resets the buffer so that you can use it again without
   * throwing away the already allocated buffer.
   */
  public void reset() {
    count = 0;
  }

  /**
   * Returns a copy of the input data.
   *
   * @return an array of chars copied from the input data.
   */
  public char toCharArray()[] {
    synchronized (lock) {
      return Arrays.copyOf(buf, count);
    }
  }

  /**
   * Returns the current size of the buffer.
   *
   * @return an int representing the current size of the buffer.
   */
  public int size() {
    return count;
  }

  /**
   * Converts input data to a string.
   *
   * @return the string.
   */
  public String toString() {
    synchronized (lock) {
      return new String(buf, 0, count);
    }
  }

  /**
   * Flush the stream.
   */
  public void flush() {
  }

  /**
   * Close the stream.  This method does not release the buffer, since its
   * contents might still be required. Note: Invoking this method in this class
   * will have no effect.
   */
  public void close() {
  }

}
